Mono-cyclononatetraenyl lanthanide complexes

The first half-sandwich complexes of the cyclononatetraenyl are reported. Coordination and deccordination of THF leads to the formation of either the ionic [Ln III ( η 3 -BH 4 ) 2 (thf) 5 ][Cnt] or the polymeric compound [La III ( η 9 -Cnt)( η 3 -BH 4 ) 2 (thf)].